Variable pitch propeller control



Feb. 29, 1944. J. H. HAMMOND, JR., ETAL 2,342,665

VARIABLE PITCH PROPELLER CONTROL Filed Sept. 26, 1942 INVENTOR Lia 4 1% a fi a/v/vaxva, J22

GEORGE A. 0L L E Y Patented 29, 1944 ,John Hays Hammond, Jr.,

Gloucester, and

George A. Colley, Newton Center, Masa; said Colley assignmto said Hammond Application September as, 1942, Serial No. 459,786

Switzerland, the details of which form no part "Claims.

This invention relates to a variable pitch propeller control system for use on towing vessels and more specifically to a system for automatically varying the pitch in accordance with variations in traction so as to maintain a constant tractioh under varying conditions.

The invention provides traction responsive means operated by the'towing mechanism, which controls means for varying the pitch of the propeller blades in such a way as to maintainthe pull on the towing cable constant.

The invention further provides means for varying the rate of change of pitch of the propeller seis and aircraft.

The invention also consists in certain new and original features of construction and combinations of parts hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its organization may be better understood by referring to the following description taken in connection with the accompanying drawing forming a part thereof,-in which The single figure illustrates diagrammatically the system as applied to the driving mechanism of a marine vessel.

In the following description and in the claims parts will be identified by specific terms for convenience, but they are intended to be as generic in their application to similar parts as the art will permit.

Referring to theaccompanying drawing, the hull of a marine vessel is indicated at II. This vessel is shown as driven by means of a propeller i2 which is provided with adjustable blades l3. The propeller I2 is attached to the end of a hollow shaft I5 which passes through an outboard bearing IS. The shaft I5 is driven by a prime mover 20 which may be of any desired, type and may be provided with a governor, not shown, for maintaining a constant speed of rotation.

The blades l3 are connected to a variable pitch mechanism l8 which may be of any well known and standard construction such as that manufactured by the Escher-Wyss Company of Zurich,

' of the present invention and are accordingly not specifically set forth herein. This mechanism, in general, comprises a rod l9 slidable longitudinally within the shaft II and connected to control the pitch or the blades l3. The rod I9 is actuated by apiston 21 in a fluid pressure cylinder 21a. Fluid for actuating the piston 21 is supplied by a pump 26 through a control valve and a distribution valve 25a which communicates with the cylinder 21:: through ducts, not shown, in the shaft I5.

A motor 2| rotates a worm 22 which operates to move the upper end of a floating lever 23, which,

in turn, is pivoted to the end of a valve rod 24 which controls the valve 25. The piston 21 is connected by a rod 28 to a collar 29 which is slidably mounted on the shaft l5 and engages the lower end of the lever 23 so that the position of this end of the lever corresponds to the pitch of the blades I3.

The upper end of the lever 23 is connected by a wire 30 to an indicator 3i which shows the pitch at which the blades 13 are set. Stops 32 are provided for limiting the maximum and minimum pitch of the blades IS. The fluid pump 25 is driven either by a motor 33 or a belt 35 from the shaft IS. A reservoir 35 and a supply tank 31 are provided for the necessary fluid.

It is to be understood that other pitch control devices may be employed in place of that referred to above, for varying the pitch of the propeller blades l3 in response to actuation of the motor 2|. A particular type is shown for purposes of illustration only.

Traction means ll are provided, which for example may be of the recording typ The traction means 4| is shown as consisting of a base 42 which is secured to the deck 43 of the vessel. Slidably mounted in the base 42 is a rod it one end of which is formed into a hook l5. Fastened to the other end of the rod 44 is a'collar 46 between which and the base 42 ismounted a compression spring 41. Attached to thehook is a towing cable 48 which may be used for towing other vessels, not shown, such for example as barges.

is provided with a pointer 58 which registers with a scale 51 graduated, for example, in thousands of pounds pull. It is to be understood that other types of direct or remote traction indicating devices may be used if desired.

In accordance with the present invention means is provided to control the motor 2i in response to the position of the pointer 56. embodiment shown a contact 58 is attached to but insulated from the pointer 56. Surrounding the scale 51 and rotatably mounted thereon is a ring 59 to which is attached a segment of a worm gear 50. Meshing with the gear 58 is a worm 8| which is rotated by means of a knurled knob 82. Mounted on but insulated from the ring 59 are a plurality of contact segments 88-48 which are selectively engaged by the contact 58.

The segments 83 and 58 are connected by iiexible leads to two conductors 1I and I2 which in turn are connected to the reversing windings of the motor 2i. The segments 64 and 65 are connected by flexible leads to two resistors I3 and H which are in turn connected to the conductor II. The segments 55 and 81 are connected by flexible leads to two resistors I5 and I5 which are in turn connected to the conductor I2. The common lead of the reversing windings of the motor 2i is connected through a battery 11 to the blade of a three position switch I8. The center contact of this switch is connected to the contact 58, the

upper contact to the conductor 12 and the lower contact to the conductor I I.

Operation In the operation of the form 01' the invention shown the pitch of the blades I3 is first set at the normal operating angle. The setting of the propeller blades I8 is accomplished by moving the blade-ofthe switch I8 into the upper or lower position which will cause the motor 2I to move the upper end of the lever 23 to the left or right to increase or decrease the pitch in a well known manner, the angle 01' pitch being indicated by the pointer of the indicator 8 I.

After the towing operation has started and the pull on the tow rope 48 has reached the desired value, as indicated by the pointer 58' on the scale 51, which may for example be 5000 pounds, the ring 59 is rotated by means of the knurled knob 52 until the insulation between the segments 55 and 58 engages the contact 58. The blade of the switch 18 is then moved into engagement with the center contact.

If the forces against which the vessel and its tow are moving should increase, such as due to encountering a strong head wind or running into a heavy sea the pull on the towing cable 48 will increase which will cause the rod 44 to move to the left against the action of the spring 41.

This will cause the pointer 55 to move in a clockwise direction showing an increase of traction. The contact 58 will then engag the segment 65 and a circuit will be closed from the battery 11 thru the resistor II to the motor 2| causing it to rotate slowly in a direction to move the upper end of the lever 23 to the right, for example. This will move the valve 2! to the right which will allow fluid under pressure to pass from the pump 25 to the cylinder 2Ia-by means of the ducts in the shaft I5. This will actuate the piston 21 which by means of the rod I9 and the link mechanism will cause the propeller blades I3 to slowly decrease their pitch. This will. cause l ss power to be transmitted from the engine 20, the R. P. M. being maintained constant by means In the of the governor, thereby decreasing the traction on the cable 48 until it again reaches 5000 pounds, at which time the contact 58 will again rest on the insulation between the segments and 68 thus stopping the motor 2|.

If the conditions under which the vessel is operating should change due to a following wind or other favorable condition so that less power is required for towing purposes the pull on the cable 48 would decrease and the reverse action wo uld take place, thus causing a gradual increase in pitch of the propellers which would cause more power to be drawn from the engine 28 until the pull on the towing cable 48 has increased to the normal value, for exan'iple 5,000 pounds. When this condition is reached the contact 58 will again rest on the insulation between the segments 65 and 68 thus stopping the motor 2|.

It the changed conditions cause a rapid change of pull on the cable 48 so that the contact 58 engages either of the segments 84 or 51 then the resistor 13 or the resistor 15 will be thrown into circuit with the motor 2I. Resistors I3 and I8 are of lower resistance than resistors II and I5 and the motor 2| will thus be caused to rotate faster, thereby changing the propeller pitch more rapidly to take care of the more rapidly changing conditions.

If the conditions change so quickly that the contact 58 engages either segment 63 or 68, then no resistance will be thrown in the circuit of the motor 2| and it will rotate at its maximum speed. thus changing the propeller pitch at a maximum rate. The stops 32 are provided so that the propeller pitch is prevented from exceeding certain limits beyond which it could not operate efliciently under any conditions.

By the systems above described the pitch of the propeller blades I3 is varied to cause the propeller to operate so as to maintain the traction of the tow rope constant, and therefore the power supplied from the engine 20, constant under varied conditions. The rate of change of pitch will vary in accordance with the change of traction so that-with a gradual change of traction there will be a slow change oi propeller pitch, thus preventing violent changes of pitch which would cause undue strain on the driving mechanism, disagreeable vibrations and ineiiiciency of the propeller, but a more abrupt change in trac tion will be promptly and quickly corrected by a more rapid actuation of the pitch control means.

In the case of an attack by the enemy it may be desirable for the tug to drop the tow and proceed at full speed immediately. This is accomplished by the present invention as the release of the tow line 48 causes the blades I3 to be immediately set at maximum pitch. The full power of the motor 20 is thus used for propelling the tug and a maximum acceleration is obtained.

Although only a few of the various forms in which this invention may be embodied have been shown herein, it is to be'understood that the invention is not limited to any specific construction but may be embodied in various forms without departing from the spirit of the invention or the scope of the appended claims.

I What is claimed is:

1. In a system for driving a vessel, a variable pitch propeller having .blades, pitch-control mechanism controlling the pitch of said blades, towing mechanism including traction responsive mechanism having meansresponsive to variations in traction in either direction from a predetermined value, and control means actuated by said traction responsive mechanism, said control means being connected to actuate said pitchcontrol mechanism to change the pitch of said blades by an amount and in a direction to restore the traction to its original predetermined value.

2. In a system as set forth in claim 1, means driving said propeller at a constant speed.

3. A system as set forth in claim 1 in which said traction responsive means is responsive to both the direction and the amount of change of traction from said predetermined'value, and said control means actuates said pitch control mechanism at a speed determined by the amount of said changeoi traction, the speed of actuation being greater for a greater change in traction and vice versa, regardless of the direction of such change.

4. A variable pitch propeller control mechanism comprising a propeller having blades, pitch-control mechanism, including a reversible control motor for varying the pitch of said blades, traction mechanism including a towing member. traction responsive mechanism responsive to variations in traction of said towing memher, said last mechanism including a movable contact member, a set of stationary contacts cooperating with said movable contact member and connected to control said reversible control motor in accordance with the extent and direction of movemen of said movable contact memher in opposite directions from a predetermined point, said control motor being connected to change the pitch of said propeller in a direction and by an amount determined by the variations in said traction from a predetermined value.

5. A variable pitch propeller control mechanism as set forth in claim 4 in which said traction responsive mechanism is connected to actuate said control motor at a speed determined by the amount of variation in traction from said predetermined value, the speed of operation be- 20 ing greater for a greater change in traction and vice versa, regardless of the direction of such change. I JOHN HAYS HAMMOND, J a. GEORGE A. COLLEY. 

